Telephone-exchange system



D. M. TAGGART.

Marginal Release Mary/na/ l'ndl.

law

I "0 W F 1 //7'V/7/0/.' flan 5 0/1/47 Tagqar/ rammed Feb. 10,1920.

DAWSON M. TAGGART, oEEAsr ORANGE, N JERSEY,YASSIGNOR.TO WEsTEaN ELECTRIC COMPANY, INCORPORATED, OF NEW, YORK, N. Y, A CORPORATION OF NEW YORK.

Application filed January 4, 1818.

To all whom it may concern:

Be it known that I, DAWSON M. TAcoA 'r, a citizen of the United States, residing. at

East Orange,'in the county of Essex and State oi": New Jersey, have invented certain new and useful Improvements in Telephone- Exchange Systems, of which the following is a full, clear, concise, and exact. description.

This invention relates to telephone exchange systems, and more particularly to such systems in which a plurality of common battery and local battery telephone lines terminating at a central oflice may be interconnected by means of link circuits located thereat. r

T he object of this invention is to provide improved signaling means for systems of this character. v r

In accordance with this invention a link circuit is provided with a relay energized when connected with a telephone line, While the supervisory relay Ofthe link circuit is deenergized, to maintain the initial energizing circuit of a recall control relay open, and, after the response of the called-tor subscriber, cooperates with the recall control relay and the supervisory-relay, to cause the intermittent operation 01 a supervisory signaling device upon the initiation of a recall by the subscriber.

This invention will be more fully understood from. the following description considered in connection with the accompanying drawing illustrating one embodiment thereof.

' There is shown in the drawing a telephone line A of the usual common battery type, which'extends from a subscribers station to a central office at which it terminates. A

local battery telephone 'line 13 also tern1i-- shown in-the drawing, and it Willbe so described.

Subscriber A, in 1n1t1at1ng a call, removes the rece1ver from the swltchhook, thereby causing the operation of line relay 5 and the lighting of line lamp 6. The operator, upon TELEPHONE-EXCHANGE Specification of Letters Patent; lgatgniged Feb; 10

Serial N0. 210,243.

observing the lighted condition of the line lamp 6, inserts plug 7 of the cord circuit G into ack 8 of line A, thereby causing the Operation of relay 9, "marginal relay 10 and cutoff relay 11, over a circuit'from battery, through the left-hand winding of .relay 9,

the winding of relay l0, sleeve contacts of theplug 7 and the jack 8, and the Winding of cutoff relay 11 to ground. Marginal re f lay 10 operates when included in circuit with a low reslstance cutofi. relay of a common battery line, but does not operate when in-- cluded in circuit with a hig'lrresistance cutofi relay of a local battery line. lay 11, in operating, disconnects the line're- Cutoff relay 5 "from the line, thereby extinguishing" 'the'line lamp 6. Marginal relay 10 in operating, disconnects the two windings of supervisory relay 15 from across the talking strands of thecord circuit C, and connects thetip strand to ground through the righthand alternate contact of relay 10, and

through its left-hand alternate contacts, con-v nects battery through the left-hand winding of uperv1sory relay 15 to the ring strand hand alternate contact of marginal relay 10,

normal contact ofsupervisory relay15 andthrough the lamp l9 and the left-hand winding-of relay- 18 in parallel, to ground. Supervisory relay 15 i thereupon energized over the talking-circuit which includes the limbs oftelephone line A. The energization of the supervisory relay 15 causes the deenergization of relay 18, and the extinguish.- ment of the lamp 19. Relay 9, in operating, closes its contact so thatupon the release of rela 18 followin the ener 'ization ofsu pervisory relay 15, relay 16 is operated over a circuit from battery, through the normally closed contact of listening key 17, the contact of relay 9, the winding of relay 16,;

right-hand normal contact of'slow-release relay 18-,g'the alternate contact of super-a visory'relay 1'5, and through the left-hand winding... of relay l8 and-thelamp in parallel to ground. Relay 18 is marginal, so that when its leit-hand'winding is shunted by the lamp 19, and is included in circuit With the winding of relay 16, it does not operate. Relay 16, however, in operating, im-

, mediately closes a locking circuit for itself through its left-hand contact, and the lefthand normal contact of relay It will be seen, therefore, that immediately upon theoperation of relay 16, the left-hand winding of relay 18and the lamp 19 are both short-circuited through the normal contact of relay 18, and the left-hand contact of relay 18.

The operator may now actuate, listeningkey 17 to connect the operators telephone set with the cord circuit. energized upon the actuation of this listening key. Afterhaving been advised by the calling subscriberA that connection is desired with the subscriber or" the local battery line B, the operator restores'listening key 17 to normal position, andinserts plug 22 into jack 23 of line B, whereuponthe cutoff relay 2 1 thereof is operatedover a circuit from battery, through the right-hand winding-oi relay 9, the winding ofmarg nal relay 25, sleeve contacts or the plug 22 and the ack 23, and the winding of cutoff relay 241 to ground. The winding of cutofi' relay 24 1S 7 of high resistance so that. marginal relay 25 does not operate. The restoration of the l1stening key 17 to normal position causes the reenergization of relay 16, and the lockingup. thereof over the previously traced ClI'Clllli.

The operator may now actuate ringing,

subscribers restore their respective receivers to the switchhooks, and, in addition, sub-.

scriber B gives a short turn of the handle of generator 28 to givea disconnect signal.

The operation of this generator causes the energlzation of supervisory relay 30, which, in attractingits armature, causes the operation of relay 31 over a circuitii'rom battery,

through the contact of listening key 17 contact of relay 9, winding of relay 31, lefthand normal contact of slow-release relay 32, alternate contact of relay 30, and lamp 33 to ground. Relay 31, in operating, establishes a locking circuit for itself through its lefthand contact and the right-hand normal contact of relay 32'to ground. Upon the re lease of supervisory relay 30'the lamp 33 is i 1 lighted over a circuit from battery, through the left-hand contact of relay 31, right-hand normal contact ofrelay 25, normal contact of, relay 30, and the lamp 33 to ground.

18 to ground;

Relay 16 is e de- The right-hand Winding of relay 32 is in parallel with the lamp 33, and this relay 32 cuit from battery, through the left-hand alternate contact of relay 10, normal contact of supervisory relay 15 and the left-hand V winding of relay 18 to ground. Relay 18, in

operating, opens a short circuit about its right-hand winding, whereupon relay 18 is locked up through its right-hand winding in series with the winding of relay 16.

' At the time the circuit is closed through the left-hand winding of relay 18, the lamp 19 is lighted, to furnish a disconnect signal. The closure of the alternate contact of relay 18 connectsan interrupter 34: to the front contact of the supervisory relay 15. If the subscriber A initiates a recall before the I operator has withdrawn-the plug 7 from the battery, through ,the interrupter 34, the

alternate contact of relay 18, the alternate contact of supervisory relay 15 and the lamp 19 to ground. The intermittent operation of this lamp serves as a recall signal. The operator, upon observing the intermittent lighting of the supervisory lamp 19,.may actuate listening key 17 to connect the telephone set with the talking circuit. The actuation of the listening key 17 opens the locking circuit of relays 16 and 18, which thereupon release their armatures, extinguishing the lamp 19.

If subscriber A does not initiate a recall, the continuous lighted condition of the supervisory lamps 19 and 33 serves as a disrestoring all apparatus to normal condition.

Should subscriber A. desire to be 7 connected with a common battery line similar to line A, the operator then inserts the plug 22 into the jack associated with the common battery line. The cutofi relay of the common battery line being of low resistance, marginal relay 25 then operates. I The op eration of the relay 25 immediately connects battery andiground to the tip. and

ring conductors or the cord circuit, and

causes the operation of relay 32 and the lighting of calling supervisory lamp, 33 over a circuit from battery, through the 'right-ln-ind alternate contact of relay 25,

winding of relay 32 in parallel to ground.

The 0 eration of-rela 32 ooens its left-' 7 P y 1 p hand normal contact,- whichis in the initial energizing circuit of relay'.31., In :this man ner the operation and locking" up of relay 31 is prevented should supervisory relay 30 be momentarily energized ,by the discharge of the condenser .connected with the line, upon the closureof the tip and ring conductors when the ringing-key 17 is restored to normal position, after ringing the call bell of the called-for line, or should the alternate contacts of the supervisory .relay be momentarily disengaged, due to the bouncing so-calledof the armature when the supervisory relay is first energized.

I The called subscriber, .in responding to the operation of the call bell, resulting from the connection ofringing current-to the line, removes the receiver from the switchhook, thereby causing the operation of supervisory relay 30. The lamp 33 is thereby extinguished, and the circuit which includesthe right-hand winding of relay 32 is opened, whereupon the relayreleases'its armatures. Upon the closure of .the left-hand normal contact ofrelay 32, relay 31 is operated over the hereinbefore traced circuit which includes the normal contact of the listening key 17, the contact of relay 9, the winding of relay 31, the left hand normal contact. of relay 32, the alternate contact. of supervisory relay 30, the right-hand windingfof relay 32 to ground. While the lamp 33 is included in parallel with the right-'hand-winding of relay 32, it 'does not lighton account of the high resistance of the-'windingof relay 31. Duetothe same reason relay .32 does not attract its armatures. Relay 31, in operating .completes a locking circuit for itself through .its right-hand contact, and the right-hand normal contact of relay32.

Atthe conclusion of the conversation the called subscriber, in'restoring the receiver to the switchhook, causes the release of the supervisory relay 30, whereupon'the lamp 33 is lighted, andthe relay 32 is operated'over a circuit from i'battery through the .rightv hand alternate contact of relay 25, normal contact of supervisoryrelay '30, and through the lamp 33 andtherightrhand-windingof relay 32 in parallel to ground. Sincethe winding of relay '31 is notincludedlinthis circuit, the lamp33 lightsiand :xthe relay 32 operates. Immediately uponthe-operation of relay 32,: the short ClIOllltlflJbOlltIltS left-hand winding :iS removed, whereupon relay 32 is locked up:in.series-.with the wind ingof relay3l. Intcrrupters3l is now conneoted with-the alternate contact of relay 32,.so that if the subscriber-in initiating another call removes :the "receiver from the switchhook before the plug. 22; is withdrawn "from the jack, supervisoryrelayf3'0 is ener-.

gized, whereupon thelamp' 33 is 1l11t61l11lt tently lighted overfa circuit :fromabattery, "through the interrupter 34, the. alternate v contact of relay 3?. --and ;the lamp :33 to ground.

Slow release relays .18 andl32yhave prc-" I ciselythesame characteristics. :Since each ofthese relays; is slow :releasmg; the momen-- tary. energiz'ation of .;either of the supenvi-f soryrelays, due. to the discharge. of'the condenser on the line upon;the;restoration-of the .ringingkey to normalflpositionyis not.

suflicientto-permit the release of the slow release relay to close the contact in circuit.

with the recall control relay 16 or In nal is prevented. It will-be understoodgthat eitherend of thecord circuits-may be em ployed ,as the answering end and either as theqcalling end.

What isclaimed is: 1

this .wayithe appearance-of a :false recall sig- I 1. A-telephone exchange system comprisingaa telephone line, a linkcircuit,;a.rel ay thereinresponsive to the-.connectionofwthe' link circuit with the "telephone :line, 2a: .sig-

nalingdevice and a secondrelayin the link :circuit,;an energizing circuit for the second relay completed upon the response L01: "the first relay, asupervisory relay inthe link circuit,arecall control relay energized upon I the energization .of-athe supervisory relay signaling device completed upon the energiz-ation. of the second relay, due; to the. de-

energization .ofzthe. supervisory i-relay fol-.

lowed .by the energization thereof.

2. A telephonelfexchange systemcompris ing a telephone "'line,-a link circuit, ;a relay.

. therein responsive ;to .the connection. of the link circuit with the telephone .;line, :a :'.;sig-- naling device and :a second relay in the. link circuit, an energizing circuit for thetvsecond,

relay completed upon :ithe :response .of the the energization of the supervisory: relay first relay, a supervisory relay in: the ilink I c1rcu1t, a recall control ,relay energized; upon and .the .denergization of the second-relay, and interrupter mechanism included inicircall control, supervisory and second relays cuit .with i the signaling device when. the rre-z and; the deenergization of thegsecond =.relay, interrupter mechanism, and a. circuitgforr the interrupter r mechanism and: the. signaling :device completed through 'a contact :fof the n second relay -whenqenergized uponthe de.-.;-

'inga telephone line, a link circuit, a relay therein responsive to the connection ofthe link circuit with the telephone line, a signalingdevice and a second relay in the link cir- V cuit, an energizing circuit for the second relay completed upon the response of the first relay, a supervisory relay in the link circuit, a recall control relay energized upon the deenergization of the second relay while the supervisory relay is energized, a locking circuit for the recall control relay established upon the energization thereof for rendering this relay independent of the condition of the supervisory and second relays, interrupter mechanism, and a circuit for the interrupter mechanism and the signaling device partially completed upon the energization of the second relay when the supervisory relay is denergizedv and fully com- 7 pletedby the subsequent energization of the supervisory relay. 5. A telephone exchange system comprls- I ing a telephone line,'a link circuit, a signaling device therefor, a local relay energized upon the connection of the link circuit with the telephone line, a supervisory relay energized upon the closure of the telephone-line,

a recall control relay, an energizing circuit therefor completed upon the energization of the supervisory relay followed by the de-. energization. of the local relay, and: inter rupter mechanism included in circuit with the slgnallng devlce uponthe subsequent energization of the local relay followed by the energization of the supervisory relay.

6. A telephone exchange system comprising a telephone line, a link circuit, a signal-' ing device therefor, a local relay energized upon the connection of the link circuit with the telephone line, a supervisory relay e'nervisory relay. 4

gized upon the closure. of the telephone'line, a recall control relay, an energizing circuit therefor completed upon the energization of the supervisory relay followed by the deenergization of the local relay, interrupter mechanism, a circuit for the interrupter mechanism and the signaling device partially established upon the energization of the local relay when the supervisory relay L is deenergized and fully established'upon the subsequent energization of the super- 7 A telephone exchangesy'stem comprising atelephone line, a link clrcuit, a s1gnaling device therefor, a local relay energized upon the'connection of the link circuit with the telephone line, a supervisory relay energizedcupon the closure of the telephone line, a recall control relay, an energizing" circuit therefor completed upon the enerT gizationof the supervlsory relay followed by the deenergization of the local relay, interrupter mechanism, and an operating circuit for the signaling device including the interrupter mechanism and contacts ofthe local and supervisory relayswhen energized.

8. A telephone exchange system comprising a telephone line, a link circuit, a signaling device therefor, interrupter mechanism,

a recall control relay adapted when energized to control the inclusion of the inter-' of the local relay followed by the energization of the supervisory relay.

9. A telephone exchange system" comprising a telephone line, a'link circuit, a signaling devicetherefor, an interrupter mech- .anism, a recall control relay adapted when energized to control the inclusion of the interrupter mechanism in circuit with the signali-ngdevice, a local relay energized upon the connection of the link circuit with the 7 completed upon the subsequent energization telephone line, a supervisory. relay in the link circult energized upon the closureof the telephone line to cause the deenergization of the local relay, an energizing circuit for the recall control relay including contacts of the energized supervisory relay and the deenergized local relay, and an operating circuit for the signalingdevice including the interrupter mechanism completed upon the subsequent energization of the local relay followed by the energization of the supervisory relay. l

10. A telephone exchange system comprising a telephone line, a linkcircuit, a signaling device therefor, an interrupter mechanism, a recall control relay adapted I when energized to control the inclusion of the interrupter mechanism in circuit with the signaling device, a local relay energized I upon the connection of the link circuit with the telephone line, a supervisory relay in the link circuit energized upon the closure of the telephone line to cause the deenercircuit for the recall control relay includi- 1'20 gization of the local relay, anenergizing ing contacts of the energized supervisory lockingcircuit. for the recall control relay established upon the energization thereof for rendering this relay independent of the condition of the supervisory and local relays, and an operating circuit for the signaling device including the interrupter.

'relay and the deenergized local relay,

mechanism partially established upon the energization of the local relay When the supervisory relay is deenergized and fully es tablished upon the subsequent energization of the supervisory relay. v

11. A telephone exchange system comprising a telephone line, a link circuit, a signaling device and a supervisory relay in the link circuit, interrupter mechanism, a recall control relay When energized cooperating With the supervisory relay to include the interrupter mechanism in circuit with the signaling device, and means in the link circuit responsive to the connection of the link circuit with the telephoneline to open a contact in the energizing'circuit of 1 the recall control relay thereby to prevent" the energization of the recall control relay upon the momentary energ zation of the supervisory relay.

' 12. A telephone exchange system" comprising a telephone line, a link circuit, a signaling device and a supervisory relay in the link circuit; an interrupter mechanism, a recall control relay when energized co operating with the supervisory relay to in- With the signaling device, and a slow release relay in the link circuit energized upon the connection of the link circuit With the telephone line and over a circuit including a contact of the deenergized supervisory relay, thereby to prevent the energization of the recall control relay upon the momentary energization of the supervisory relay,

In Witness whereof I hereunto subscribe my name this 29th day of December, 'A. D.

DAWSON M. TAGGART.

clude the interrupter mechanism in circuit: 

